[Elecraft] KX3: thermal frequency drift

Eric Swartz - WA6HHQ, Elecraft eric at elecraft.com
Fri Apr 11 20:35:01 EDT 2014


The XG3 is perfect for this calibration. Freq is not critical as ling as its 
close to 50. Our XG50 is actually a little below 50 Mhz. (I think it used the 
ref oscillator module from the K3.)

Eric
elecraft.com

On 4/11/2014 1:39 PM, Edward R Cole wrote:
> It was suggested I do the Temp Compensation Procedure.  Unfortunately I do not 
> have a stable 50-MHz signal source. However I did run the Reference Frequency 
> Calibration using my XG3.  Call this "Part Two":
>
> I sampled the RF output of the XG3 with my counter and also input that to the 
> KX3 for the Calib.  This required running at 0 dBm to inject strong enough 
> signal for the counter (approx -3 dBm).  I turned on the ATT for the KX3 to 
> keep input from overdriving.  Got about S9 signal level.
>
> I got it adjusted to within about 2-Hz.  The XG3 drifts approx +/- 2 Hz so 
> difficult to set the Ref*Frequency using it.  But that eliminated most of the 
> 38 Hz offset I saw last night.  Running the Tx at 5w afterward drift was in 
> the range of 0 to +7 Hz for a 50-second key down run.  The drift is not steady 
> in one direction so average error is probably in the neighborhood of +5 Hz 
> with 5-Hz uncertainty in the measurement.  Crude but gives a ballpark idea 
> what to expect.
>
> Today's measurements were all with new heat sink installed.  Temp Comp. 
> probably would lower these numbers a bit.
>
> I might try running my K3 as signal source for Temp Comp. if it holds more 
> stable then the XG3 at 50-MHz.  I am using the EXREF so it may be better?
>
> 73, Ed - KL7UW
> http://www.kl7uw.com
>     "Kits made by KL7UW"
> Dubus Mag business:
>     dubususa at gmail.com
>
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